The present invention relates to the therapeutic treatments of blood vessels and possibly other body passages, and particularly treatments in which a chemical agent, antibodies, other biological material, or modified cells are brought into contact with, or implanted in, the wall of a body passage in order to reverse or prevent a pathogenic condition.
Medical research has led to the discovery of a number of treatments of this type which may be developed into clinically useful procedures. Examples of such treatments are described in Nabel et al, Recombinant Gene Expression in Vivo Within Endothelial Cells of the Arterial Wall, SCIENCE, Vol. 244, Jun. 16, 1989, pages 1342-4.
However, clinical application of such treatments requires a procedure which can be performed in vivo without giving rise to any unacceptable side effects.
In the case of blood vessels, this generally means that the material to be applied to the vessel walls must be confined to the treatment site. Otherwise, it would be necessary to introduce a large quantity of treatment material into the vascular system, with the attendant danger of harmful side effects.
A second requirement which exists in the case of treatment of blood vessels is that a sufficient flow of blood be maintained past the treatment site, particularly if the treatment requires a prolonged period of exposure of the vessel wall to the treatment material.
Finally, it appears that many treatments of the type here under consideration can be performed effectively or optimized only if the proportion of treating material in the fluid at the treatment site is maintained within a defined range.
U.S. Pat. No. 4,423,725, which issued to O. E. Baran on Jan. 3, 1984, describes an intervention device composed of a catheter having a blood flow lumen, a chemical delivery lumen and a suction lumen, associated with two annular cuffs which are inflatable to isolate a blood vessel region containing an obstruction. This patent discloses the treatment of blood vessel obstructions by balloon angioplasty followed by the application of anticoagulant drugs or cholesterol diluting drugs. A similar device for performing chemical dissolution treatments is disclosed in U.S. Pat. No. 4,610,662, which issued to Weikl et al on Sep. 9, 1986.